Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in CPP):

Solution:
#include<bits/stdc++.h>
#define F first
#define S second
using namespace std;

int main(){

  int H, W;
  char mas[55][55];
  int dx[] = {1, 0, -1, 0}, dy[] = {0, 1, 0, -1};
  int d[55][55];
  typedef pair < int, int > P;
  queue < P > que;
  int cnt = 0;

  cin >> H >> W;
  for(int i=1;i<=H;i++){
    for(int j=1;j<=W;j++){
      cin >> mas[i][j];
      if(mas[i][j] == '.') cnt++;
    }
  }


  memset(d, -1, sizeof(d));

  que.push(P(1,1)); //x, y
  d[1][1] = 0;

  while(que.size() != 0){
    int x = que.front().F, y = que.front().S; que.pop();

    for(int i=0;i<4;i++){
      int nx = x + dx[i], ny = y + dy[i];

      if(nx < 1 || ny < 1 || nx > W || ny > H) continue;
      if(mas[ny][nx] == '#') continue;
      if(d[ny][nx] != -1 && d[ny][nx] <= d[y][x]+1) continue;

      d[ny][nx] = d[y][x] + 1;
      que.push(P(nx, ny));
    }
  }

  if(d[H][W] != -1) cout << cnt - d[H][W] -1 << endl;
  else cout << -1 << endl;

}